A wide variety of electrical connectors require protection against the egress or ingress of radio frequency interference (RFI) and/or electromagnetic interference (EMI). This is particularly true in electrical connectors used with high speed electronic equipment. "EMI" has become fairly generic to describe most types of interference caused by electronic waves.
EMI protection typically is provided by substantially enclosing a connector, at least about its mating interface, with an electrically conductive shield. Such shielding enclosures typically are stamped and formed from sheet metal material. The shields are grounded, such as to a ground wire of an electrical cable or to a ground circuit trace on a printed circuit board. When two connectors are mated, it is desirable to have the shields of the two connectors in positive engagement to establish a common ground therethrough and to prevent electromagnetic radiation from or to the connectors in the area of the mating interface thereof.
Heretofore, EMI protection at the interface of a pair of mating connectors has been accomplished simply by overlapping the two shields of the respective connectors. Although this method is quite effective, it requires additional space in the mating direction of the connectors and this is highly undesirable when space is critical in miniaturized, high speed electronics. The same type of space problem arises when radially extending flaps are used between the shields to establish positive engagement, with the space problem being in the transverse direction rather than the mating direction.
In order to solve the space problems described above, positive engagement between a pair of shields of a pair of mating connectors has been accomplished by using flexible, cantilevered ground arms which are stamped directly out of a side wall of at least one of the shields at the mating interface of the connectors. Although such flexible ground arms do not require additional space, they create further problems in creating stamped openings about the arms through which electromagnetic interference can pass. In addition, if the flexible arms are too short, they are susceptible to failure due to stress and strain from numerous mating and unmating cycles of the connectors. In other words, it is desirable to have relatively long cantilevered ground arms, but the size of connectors often do not allow sufficient dimensions to lengthen the arms. The present invention is directed to solving one or more of this myriad of problems in shielded electrical connectors.